A master cylinder of this kind is known from DE 10 2004 057 137 A1, which is incorporated by reference, for example, wherein the control passages are provided as radial transverse holes of small cross section and an encircling inner groove is formed on an inner side in the region of the transverse holes in order to minimize the idle travel of the master cylinder and, at the same time, to reduce the throttling resistance by reducing the length of the transverse holes.
In the case of use in a regulated braking system, such as a braking system with anti-slip regulation (ASR) or an electronic stability program (ESP), additional pressure medium is drawn in from a pressure medium reservoir via the master cylinder by a pump in the case of a control intervention. The disadvantage here is that the small cross section of the transverse holes produces an excessive flow resistance, and the pressure medium required cannot be made available quickly enough to the pump.
In order to reduce the flow resistance, there is the possibility, in the case of the known master cylinders, of providing a larger number of transverse holes or of optimizing the transverse holes in respect of the diameter thereof. However, a disadvantage of the first-mentioned solution is found to be the fact that the flow resistance is reduced in favor of the stability of the piston and, furthermore, that the provision of a large number of small transverse holes is economically disadvantageous. The second solution has the disadvantage that the idle travel (closing travel) of the master cylinder is increased by displacing the controlling lateral edge of the holes.